Switch assembly



Marh l2, 1940.

w. c. FURNAs l1-:1F A1.

SWITCH ASSEMBLY Filed oct. 6. 1938 2 sneersfsneet 1,

ATTORNEY Mmh 1?,l 1940..

w. c. FuRNAs r fu. 2,193,127

SWITCH ASSEMBLY Filed Oct. 6, 1938 2 Sheets-Sheet 2 n INVENOR Y @QMATTORNEY Patentedl Mar. 12, 1940 SWITCH ASSEMBLY William C. Furnas andGilbert H. Hansen, West Allis, Wis.; said Hansen assigner to saidFurnas, a sole trader doing business as Furnas Electric Company, WestAllis, Wis.

Application October 6,

17 Claims.

Our present invention relates generally to lmprovements in the art ofcontrolling electrically actuated apparatus, and relates morespeciiically to improvements in the construction and operation of iiuidpressure actuated switches of the general type shown and described incopending application Serial No. 138,296, illed April 22, 1937.

Generally dened, an object of our present invention is to provide animproved automatic pressure switch assembly which is simple inconstruction and highly eiilcient in operation.

It is frequently desirable when utilizing fluid pressure actuated switchmechanisms for controlling the operation of electrically operatedapparatus such as the motor driving a compressor, to be able to quicklyand accurately adjust the pressure range at the ends of which the switchwill close and open respectively. In some cases, it may be desirable toadjust this pressure range without varying the magnitude, while in othercases it may be preferable to increase or diminish the magnitude alonein either direction, while in still other instances it may becomedesirable tovary the position of this range as well as its magnitude.For example, the switch may be initially set for closing operation attwenty pounds pressure andto open at thirty pounds, and it maybedesirable to effect closing at fifty ,pounds and opening at sixty poundspressure thus preserving the ten pound magnitude of the range. Thenagain, it may be desirable to change the initial ten pound range ofoperation to fteen pounds, whereby the switch might again close attwenty and open at thirty pounds, or close at fifteen and open at thirtypounds pressure. On

the other hand, it may be desired to change from the initial twenty andthirty pound limiting positions, -to a fifty pound low and sixty-livepound high pressure range. While it has heretofore been proposed andattempted to provide switch adjusting mechanism for effecting some ofthese desirable variations in operating conditions, the prior proposedmechanisms are not- 1938, Serial No. 233,520

(Cl. 20G-83) tions in the source of uid pressure which actuates theswitch.

A further specific object of the present invention is to provideimproved switch mechanism of simpliiled and compact construction, theessential parts of which may be readily, accurately and economicallymanufactured from sheet metal with the aid of. punches and dies.

Still another specillc object of our invention is to provide an electricswitch, which is well insulated and protected, and which may be safelyoperated either automatically or manually.

A n additional-specific object of the invention is to provide variousimprovements in the details of construction of switches, especially ofthe automatic iiuid pressure actuated type, whereby such devices may bedurably manufactured at minimum cost.

These and other specific objects and advantages of our invention will beapparent from the following detailed description.

A clear conception of embodiments of the several features constitutingthe present invention, and of the mode of constructing and of operatingfluid pressure actuated electric switches built in accordance with ourimprovement, may be had by referring to the drawings accompanying andforming a part of this specification.

Fig. 1 is a longitudinal central vertical section through one of ourimproved fluid pressure actuated switches, showing the same releasedlfor automatic operation and with Ithe contacts opened by fluidpressure;

Fig. 2 is a similar section through the sameswitch with the contacts inclosed position; 35

Fig. 3 lis a transverse vertical section through the switch taken alongthe line 3 3 of Fig. 1;

Fig. 4 is a. top view of the switch assemblage of Figs. 1, 2 and 3 withthe closure cover removed;

Fig. 5 is a side elevation of the main frame and 40 some of the toggleand actuating elements of the switch assemblage, showing the toggleelements locked in contact open position by the 4manual control means;

Fig. 6 is a rear view of the portion of. the switch mechanism'shown inFig. 5, showing the elements in the same position;

Fig. 'l is a transverse horizontal section through the switchassemblage, the sectionvbeing taken along the line 1-1 of Fig. l; and 50Fig. 8 is another transverse horizontal section through the switch,taken along the line 8-8 of Fig. 1.

Referring to the drawings, our improved fluid pressure actuated switchas shown therein, comprises in general a main frame having a circularbase III riveted or otherwise rigidly attached to an upper portion IIwhich is provided with integral side walls I2 and flanges I3, and withan integral front wall I4 contiguous with but extending somewhat abovethe side walls I2; a lower casing I5 with the bottom of which the framebase III coacts, and which is provided with a large central opening I1;a flexible diaphragm I6 coacting with the lowermost face of the casingI5 and spanning the opening I1 therein; a fluid pressure connection orfitting I8 having a flange I8 which is clamped against the diaphragm I6and/to the casing I5 and base III, by means of screws 20; an invertedconical member 2I secured to the fltting I8 and having a restrictedfluid inlet opening 22 at the apex of the cone; a helical spiral spring2 I coacting with the flange I9 and with the center of the diaphragm I6;a motion transfer element or disk 23 coacting with the diaphragm I6 andhaving a central conical stop 24 adapted to engage the base IIJ, andintegral side projections 25 extending upwardly through the opening I1and through holes in the base II) adjacent the side walls I2; a mainU-shaped toggle member or bracket 26 having opposite side arms 21 formedwith notches 28 which are engageable by the disk projections 25, thebracket 26 being swingable adjacent to the walls I2 upon integral inwardextensions 29 coacting with notches 3ll`formed in the front upperportions of these walls I2; a primary adjusting spring 3l coacting witha retaining flange 32 formed integral with the rear central portion ofthe bracket 26 and reacting against a nut 33 having screw threadcoaction with a bolt 34 the lower head 35 of which is fitted in a recess.36 in the base III and the upper threaded end of which extends upwardlya considerable distance; a cam 31 carried by a shaft 33 journalled in asocket 39 formed in the base I0 and in the casing I5, the shaft 38having an external handle 48 for positioning the cam 31 so as topositively lock the toggle bracket 26 in switch open position; anauxiliary U-shaped toggle member 4I having arms 42 provided with outwardextensions 43 coacting with rear notches 44 formed in the rearupperportions of the side walls I2, the member. being swingable betweenthese walls and having lower stop lugs 45 cooperable with the bottom ofthe frame portion II to limit the down-swing, and being cooperable withthe head of a differential adjusting screw 46 carried bythe front wallI4 to limit the upswing of the member 4I; a toggle actuating spring 41coacting with central projections 48, 48 of the toggle members 26, 4Irespectively; a pair of parallel movable switch contact carrying-bars5I) slidable in slots formed in upper and lower plates 5I, 52respectively, secured to the frame flanges I3, the bars 56 havingnotches 53 in their lower rear portions forming vertically spacedabutments with which portions 54 of the toggle member 4I are cooperable;four movable contacts 55 carried by transverse plates 56 secured to themedial portions of the bars 56; compression springs 51 embracing thebars 50 and coacting with the adjacent pl'ates 56 and with the flxedlower plate 52; four fixed contacts 58 secured to the upper plate 5I andeach having a conductor attaching screw 59 associated therewith; a flashpreventing shield 60 secured to the frame flanges I3 by means of aspring clip 6I provided with side slots coacting with lugs 62 formedintegral with the flanges I3; and a removable cover 63 coacting with thecasing I5 and being held in normal closing position by means of aclamping nut 64 coacting with the threaded bolt 34.

` The frame base III and portion I I as well as the casing I5, fittingI8, disk 23, toggle members 26, 4I, plates 56, clip 6I and cover 63 maybe formed of sheet metal with the aid of punches and dies; and thecasing I5 is provided with front openings 65 i'or the electrical switchconnections, and also has an identification plate 66 at the side thereoffor partially closing the slot through which the handle 46 is insertibleduring assembly of the mechanism, see Figs. 3, 4, 7 and 8. The upper andlower transverse plates 5I, 52, the movable bars 50 and the shield plate60 are-all formed of insulating sheet material, and the diaphragm I6 isformed of flexible material such as rubber. The inverted conical member2I which is rigidly attached within the fitting I8 and is provided withthe small hole 22, is provided for the purpose of preventing suddenfluctuations or pulsations in the actuating fluid pressure, fromundesirably affecting the movement of the toggle, and the helical spiralspring 2| which constantly presses upwardly against the diaphragm I6serves to prevent the projections 25 o! the disk 23 from leaving thesockets or notches 28 formed in the side arms 21 of the-toggle bracket26.

The cam 31 for locking the switch in open position, is shown in inactiveposition in Figs. 1 and 2, and in effective position in Figs. 5 and 6.This cam 31 is engageable with the under side of the toggle member orbracket 26 when the manipulating handle 40 isset upright as in Figs. 5and 6, and has two stop lugs 61, 68 of which the lug 61 engages thebracket 26 when the switch is locked open, while the lug 68 engages theframe portion II when the cam 31 is inactive. The shaft 38 which carriesthe cam 31, is provided with a flattened portion 69 with which a rodspring 16 is engageable to normally retain the cam 31 in inactiveposition, and the spring 10 may be supported from the main frame portionI I as shown in Fig. 8.

The two toggle members 26, 4I are independently swingably suspended fromthe side walls I2 of the stationary main frame, the member 26 beingswingable about the extensions 28 and notches 3II from the front portionof the frame, andthe member 4I being likewise swingable from the frameabout the extensions 43 and notches 44. The compression spring 41 servesto throw the toggle member from one extreme position to the other with adecided snap action, and by virtue of the fact that the member portions54 are engageable with the opposite ends of the lostmotion cut out ornotches 53 of the movable switch bars 60, the movable contact 55 will besimultaneously moved from one extreme position to the other with asimilar snap action. The pressure limits of the range of action of thefluid pressure acting upon the diaphragm, are simultaneously but notequally adjustable by varying the tension of the adjusting spring 3lwith the aid of the nut 33 coacting with the bolt 34. The

high pressure limit of this range is also variable by means of thedifferential adjusting screw 46 the head of which provides a stop forlimiting the upward swinging motion of the toggle member 4|, as shown inFig. 2. For example, if the switch is initially operable with a tenpound differential or range and is set`to close at twenty pounds persquare inch gage pressure acting on the diaphragm I6, and to close atthirty pounds per inch; the tension of the spring 3| may be increased tocause the switch to close at say fifty poundsl but the opening pressurerequired will then be approximately sixty seven instead of sixty pounds,thus having increased the ten pound range to seventeen pounds. Bymanipulating the differential screw 46, the ten pound differential orrange may again be reestablished from fifty to sixty pounds, withoutmaterially affecting the lower limit of this range. The adjusting screw46 may also be utilized to vary the diiierential or range of action ofthe toggle without adjusting the spring 3|, as for'example, bymaintaining the initial twenty pound lower limit and by raising thethirtypound upper limit to thirty five, thereby increasing the originaldifferential from ten to fifteen pounds.

The compression springs 51 which coact with, the plates 52, 56, functionto oppose the toggle action and to constantly urge the movable contacts55 upwardly. When the mechanism is positioned as shown in Fig. 1 withthe switch open, the toggle member 4| is swung downwardly and engagesthe lower ends of the notches 53 thereby compressing the springs 51, butwhen the toggle is swung to the position shown in Fig. 2, the springs 51quickly become effective to slide the bars 50 upwardlyand to therebyclose the switch. 'I'he movable contacts 55 are rounded` as shown, buttheiixed contacts 58 are fiat faced, thereby insuring perfect contact atall times, and the plates 56 which carry the movable contacts 55 arepreferably loosely mounted upon the bars 50 so as to permit the springs51 to equalize the contact pressures. The upper plate 5| which carriesthe xed contacts 58 is reenforced adjacent to these contacts bytransverse upper strips 1| which also provide longer guide slots for themovable bars 5l), and the xed contacts are secured to fasteners- 12having square portions 13 coacting with square holes in the plate 5I,see Fig. 1. The fasteners 12 are rivetted to terminal receptacles 14which are provided with cut-outs 15 as shown in Fig. 4 so as to separatethe lead wires, and the screws 59 coact with internal threads in thefasteners 12. The flash shield 60 protects the spring 3| from arcing,and also provides an insulated receptacle or housing for the switchcontacts 55, 56, and the plates 5|, 52 are secured to the anges I3 bymeans of end lugs 16 as illustrated in Fig. 4. The cover 63 completesthe switch enclosure, but this cover is readily removable for adjustmentand inspection purposes, by merely removing the thumb nut 64.

During normal operation of our improved switch assembly, when the handle40 is in upright position as shown in Figs. 5 to 8 inclusive, the switchis open and the cam 31 is effective to hold the switch in this positionby virtue of the coaction between the cam 31 and the toggle member 26.During such positioning of the switch, the diaphragm I6 may or may notbe subjected to fluid under pressure, and the spring 2 I will functionto retain the projections 25 in engagement with the sockets 28 of thebracket member 26, in case there is insuicient iluid pressure acting onthe diaphragm to so retain the projections 28-of the disk 23. When thecam 31 is positioned as in Figs. 1 and 2, the adjusting nut 33 may bemanipulated to predetermine the range of automatic operation of theswitch mechanism, and assuming the spring 3| to have been thus adjustedso as to cause the toggle to throw over center in one direction when thepressure falls to a low limit of say twenty pounds and in the oppositedirection when the fluid pressure reaches a maximum of fthirty pounds,then the switch will be closed during automatic operation when the fluidpressure acting on the diaphragm drops to twentn pounds and the switchwill be automatically opened when this pressure reaches thirty pounds.The gradual increase in pressure will obviously cause movement to betransmitted to the main toggle member or bracket 26 through the disk 23and projections 25 to thereby cause the member 26 to swing about theextensions 29 in an upward direction. When the movement of th member 26becomes suflicient to permit the compression spring 41 to becomeeffective, this spring acts quickly to swing the auxiliary toggle member4| /about its pivot extensions 43 to the position indicated in Fig. 1,whereby the movable contacts 55 will be snapped into open position. Thisactual snapping will not occur until the pressure acting upon thediaphragm 16 has increased from twenty pounds initial pressure to thirtypounds maximum. As the pressure acting upon the diaphragm I5 graduallydiminishes, the spring 3| becomeseffective to push the member 26downwardly until the spring 41 again becomes effective to swing theauxiliary toggle member 4| in the opposite direction and into theposition shown in Fig. 2. It will thus be apparent that the action ofthe improved switch mechanism when the cam 31 is ineffective, isentirely automatic and that the switch contacts are quickly opened andclosed when the toggle mechanism becomes effective.

If it becomes desirable to vary either the range of pressure which willbe effective in actuating the switch, or the position of this range,such adjustments may be quickly and accurately eii'ected. In order tovary the range of pressure, it is onlynecessary to manipulate thedifferential adjusting screw 46 which limits the throw of the togglewithout varying the tension of the toggle spring 41.` For example, ifthe initial range is ten pounds and it is desired to have an initialrange of fifteen poundsnthen it is only necessary to manipulate thescrew 46 so as to vary the extent of the toggle throw. If, however, itis desired to vary the position of the range, as for instance from aninitial position of from twenty to thirty pounds, to a nal position offrom fifty to sixty-five pounds, then it is necessary to manipulate thenut 33 so as to correspondingly increase the compression of the primaryspring 3|. If it becomes desirable to vary the position of the rangewithout increasing or diminishing the pressure range itself, then bothadjustments may be utilized. For example, the spring 3| would beadjusted to vary the position of the' range and such adjustment wouldnecessarily also vary the magnitude of the range and such variationmight be from an initial range of ten pounds to a subsequent range offifteen pounds. The adjusting screw 46 may then be manipulated so as toreturn the pressure range to ten pounds or the initial value. Animportant feature of our present improved adjusting mechanism is thefact that the pressure range position adjustment is effected by varying,the tension of a spring; while the adjustment for varying the pressurelimits relative to each other, is effected by merely increasing ordiminishing the toggle throw and without varying the tension of springs.It will thus be apparent that with the improved adjusting ,mechanism anydesired conditions of operation may be quickly and effectively obtainedwith minimum effort and without the use of tools other than a screwdriver and a wrench. These adjustments may be effected upon removal ofthe cover 63, and when proper adjustment has been obtained the cover 63should again be applied so as to conceal and protect the mechanism.

From the foregoing detailed description it will be apparent that ourpresent invention provides an extremely simple, compact and reliableswitch mechanism which is automatically operable and which may beconveniently adjusted to produce any desired operation. By mounting bothtoggle members 26, ll'on the stationary frame rather than upon eachother, a more sturdy and reliable `assemblage results, and it has alsobeen found that such mounting permits more accurate adjustment of thepressure limitsl and pressure ranges. rIhe improved adjusting mechanismis obviously durable in construction and can be conveniently manipulatedto produce accurate results, and the cone 2| with its relatively smallinlet opening 22 functions to eliminate objectionable operation due tosudden iluctuations in the fluid pressure source. The spring 2|maintains the vmotion transmitting element 23 in insulating plates,movable contact effective operating condition at all times, and the cam31 provides simple and effective means for permitting manual actuationof the switch in case the automatic operation is not desired. 'I'hemanual actuating mechanism is extremely simple and compact and can bequickly and conveniently installed. The switch contacts 55, 58 areeffectively confined and protected and the mounting of the movablecontacts 55 insures efficient closing at all times. The improvedconstruction oi' the stationary contact supports prevents the contacts58 from becoming loose due to .continued operation, and the leadreceptacles 14 are vso constructed that they will avoid danger ofpossible short circuiting of the connections leading to the switch. Byvirtue of the fact that all of the main elements of the structure areadaptedto be formed of sheet metal with the aid oi' punches and dies,the assemblage can obviously be manufactured and sold at extremelymoderate cost, and switches constructed in accordance with thisimprovement have proven highly satisfactory in actual commercial use.

It should be understood that it is not desired to limit this inventionto the exact details of construction-and to the precise mode ofoperation, herein shown and described, for various modications in thescope ofthe claims may occur to persons skilled in the art.

We claim:

1. In combination, a frame, spaced insulating plates secured to saidframe, stationary contacts secured to one of said plates, movablecontact carrier bars slidably coacting with both of said supportsloosely suspended from said bars, springs interposed between the otherof said plates and said supports, and toggle means for moving said barswith a snap action.

2. In combination, a frame, spaced insulating plates secured to saidframe, a fixed contact carried directly by one of said plates, a movablecontact carrier bar slidable in alined slots in said plates, a movablecontact support loosely suspended from said bar, a spring coacting withsaid support to permit said bar to continue its movement after themovable contact has engaged said fixed contact, and means for slidingsaid bar in said slots to impart a snap closing action to said contactsupport.

3. In combination, a frame, parallel plates secured to said frame,stationary contacts carrled by one of said plates, movable contactcarrier bars slidably coacting with both of said plates, movable contactsupports loosely suspended from said bars, coil springs interposedbetween said movable contact supports and the other of said plates, andmeans for simultaneously moving said y bars with a snap action.

4. In combination, a frame having spaced side walls, parallel insulatingplates secured to said Walls to provide an intervening space, astationary contact suspended from one of said plates, a movable contactcarrier bar slidable through said space, a movable contact slidablysuspended from said bar within said space, a spring interposed betweensaid movable contact and the other of said plates, and means for movingsaid bar with a snap action.

5. In combination, spaced plates, a stationary contact suspended fromone of said plates, a bar slidable across the space between said plates,a movable contact slidably suspended from said bar, a spring interposedbetween .said movable contact and the other of. said plates, and meansfor moving said bar longitudinally with a snap action.

6. In combination, a metal frame having laterally spaced side walls,parallel insulating plates secured to said walls to provide anintervening space, iixed contacts secured to one of said plates withinsaid space, movable contact carrier bars slidable through said space,movable contacts slidably suspended from said bars, spring meansinterposed between said movable contacts and the other of said plates,actuating means disposed `outside of said space for imparting movementto said bars, and another insulating plate coacting with said parallelplates to shield said space from said actuating means.

'7. Incombination, a cup shaped casing having a iluid pressure actuatedat the bottom of the cup, a sheet metal frame disposable within saidcasing and having a base and integral side walls, relatively movableswitch contacts carried by said side walls remote from said base, afluid pressure actuated toggle lever fulcrumed on said side wallsbetween said base and said contacts, a motion transmitting memberloosely interposed directly between said diaphragm and said lever, acontact actuating toggle lever fulcrumed on said side walls andcooperating with said fluid pressure actuated lever to impart a snapclosing action to said contacts, and a cam journalled in said frame andbeing manually operable from the exterior of said casing to move saidfluid pressure actuated lever to contact closing position.

8. In combination, a cup shaped casing having a fluid pressure actuatedat the bottom of the cup, a sheet metal frame disposable within saidcasing and having a base and integral side Walls, relativelyl movableswitch contacts carried by said side walls remote from said base, ailuid pressure actuated toggle lever fulcrumed on said side wallsbetween said base and said contacts, a motion transmitting member havingloose surface contactwith said diaphragm and being provided withlaterally spaced projections engaging said toggle lever to move thesame, a contact actuating toggle lever fulcrumed on said side Wallsremote from the fulcrums of said iiuid pressure actuated lever, and amanually operable cam' journalled in said frame and coacting directlywith said fluid pressure actuatedv lever to render the iluid pressureinactive.

9. In'combination, a sheet metal frame having a base and integral sidewalls, a fluid pressure actuated lever having side arms fulcrumed on thefront edges of said walls and extending along the outer sides thereof,relatively movable contacts carried by said walls above said lever, andanother lever fulcrumed on the rear edges of said walls and extendingbetweenthe same and disposed between said contacts and fluid pressureactuated lever, said levers cooperating to form a toggle for imparting aclosing snap action to said contacts.

10. In combination, a sheet metal frame having a base and integral sidewalls, a fluid pressure actuated lever having side arms fulcrumed on thefront edges of said walls, and extending along the outer sides thereof,relatively movable contacts carried by said walls above said lever, acontact actuating lever having side arms fullcrumed on the rear edges ofsaid walls and located therebetween, and a spring connecting said leversto provide a snap action actuating toggle for said contacts.

4 1l. In combination, a sheet metal frame having a base and integralside walls, a fluid pressure actuated lever having side arms fulcrumedon the front 'edges of said walls and extending along the outer sidesthereof, relatively movable contacts carried by said walls above saidlever, a contact actuating lever having side arms fulcrumed on the rearedges of said wallsand located therebetween, a spring connecting saidlevers to provide a snap action actuating toggle for said contacts, anda manually operable cam journalled in said frame and coactng directlywith said fluid pressure actuated lever to render the fluid pressureineffective.

12. In combination, a sheet metal frame having a base provided withintegral side walls and an end wall, relatively movable contactssupported by said frame, a fluid pressure actuated lever fulcrumed onsaid side walls, a contact actuating lever fulcrumed on said side walls,said levers cooperating to provide a contact actuating toggle, and ascrew extending parallel to said front wall and coactng with one of saidlevers to limit the toggle movement. f

13. In combination, a sheet metal frame having a base provided withintegral side walls and an end wall, said end wall having a laterallyoff-set integral portion providing a threaded socket extending parallelto said wall, relatively movable contacts supported by said frame, afluid pressure actuated lever fulcrumed on said side walls near saidfront wall, a contact actuating lever fulcrumed on said side wallsremote from said front wall, said levers forming a contact actuatingtoggle, and'a screw coactng with said socket to limit the movement ofsaid levers.

14. In combination, a frame having relatively movable contacts suspendedtherefrom, a toggle lever movable to open and close said contacts Iwitha snap action, a fluid pressure actuated toggle lever cooperating withsaid contact moving lever to provide a toggle, a fluid pressure operablediaphragm for moving said fluid pressure actuated lever, means forming afluid confining chamber exposed ,to said diaphragm, and a sheet metalcone having a pin hole at its apex for admitting fluid under pressure tosaid chamber.

15. In combination, a frame having relatively movable contacts suspendedtherefrom, a. toggle lever movable to open and close said contacts witha snap action, a fluid pressure actuated toggle lever cooperating withsaid contact moving lever to provide a toggle, a fluid pressure operablediaphragm for moving said fluid pressure actuated lever, means forming afluid confining chamber exposed to said diaphragm, and a sheet metal`cone having a pin hole at its apex for admitting fluid under pressureto said chamber, the apex Ation relative to said lever.

17. In combination, a frame having side walls, spaced insulating platessecured to said walls, switch contacts confined within the space betweensaid walls and said plates, means for actuating said contacts, a4 shieldplate coactng with said walls to insulate said contacts from saidactuating means, and a spring clip coactng with said shield plate andwith said side walls to detachably retain said shield plate in position.

WILLIAM C. FURNAS. lGZILBERT H. HANSEN.

